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  2. Regular icosahedron - Wikipedia

    en.wikipedia.org/wiki/Regular_icosahedron

    The 600-cell has icosahedral cross sections of two sizes, and each of its 120 vertices is an icosahedral pyramid; the icosahedron is the vertex figure of the 600-cell. The unit-radius 600-cell has tetrahedral cells of edge length 1 φ {\textstyle {\frac {1}{\varphi }}} , 20 of which meet at each vertex to form an icosahedral pyramid (a 4 ...

  3. Euler characteristic - Wikipedia

    en.wikipedia.org/wiki/Euler_characteristic

    where V, E, and F are respectively the numbers of vertices (corners), edges and faces in the given polyhedron. [2] Any convex polyhedron's surface has Euler characteristic = + = . This equation, stated by Euler in 1758, [3] is known as Euler's polyhedron formula. [4]

  4. Icosahedron - Wikipedia

    en.wikipedia.org/wiki/Icosahedron

    Construction from the vertices of a truncated octahedron, showing internal rectangles. The Cartesian coordinates of the 12 vertices can be defined by the vectors defined by all the possible cyclic permutations and sign-flips of coordinates of the form (2, 1, 0). These coordinates represent the truncated octahedron with alternated vertices deleted.

  5. Final stellation of the icosahedron - Wikipedia

    en.wikipedia.org/wiki/Final_stellation_of_the...

    The 92 vertices lie on the surfaces of three concentric spheres. The innermost group of 20 vertices form the vertices of a regular dodecahedron; the next layer of 12 form the vertices of a regular icosahedron; and the outer layer of 60 form the vertices of a nonuniform truncated icosahedron. The radii of these spheres are in the ratio [11]

  6. Vertex configuration - Wikipedia

    en.wikipedia.org/wiki/Vertex_configuration

    A vertex configuration is given as a sequence of numbers representing the number of sides of the faces going around the vertex. The notation "a.b.c" describes a vertex that has 3 faces around it, faces with a, b, and c sides. For example, "3.5.3.5" indicates a vertex belonging to 4 faces, alternating triangles and pentagons.

  7. Truncation (geometry) - Wikipedia

    en.wikipedia.org/wiki/Truncation_(geometry)

    Types of truncation on a square, {4}, showing red original edges, and new truncated edges in cyan. A uniform truncated square is a regular octagon, t{4}={8}. A complete truncated square becomes a new square, with a diagonal orientation. Vertices are sequenced around counterclockwise, 1-4, with truncated pairs of vertices as a and b.

  8. Platonic solid - Wikipedia

    en.wikipedia.org/wiki/Platonic_solid

    The coordinates of the icosahedron are related to two alternated sets of coordinates of a nonuniform truncated octahedron, t{3,4} or , also called a snub octahedron, as s{3,4} or , and seen in the compound of two icosahedra. Eight of the vertices of the dodecahedron are shared with the cube.

  9. Jessen's icosahedron - Wikipedia

    en.wikipedia.org/wiki/Jessen's_icosahedron

    The vertices of Jessen's icosahedron may be chosen to have as their coordinates the twelve triplets given by the cyclic permutations of the coordinates (,,). [1] With this coordinate representation, the short edges of the icosahedron (the ones with convex angles) have length 6 {\displaystyle {\sqrt {6}}} , and the long (reflex) edges have ...